Proj 11x: Stealing Cookies with XSS (10 pts.)

What You Need

A computer with Firefox. Don't use Chrome.

Task 1: Finding an XSS Vulnerability

You need a page that allows login, creates cookies, and has an XSS vulnerability. We'll use the one I made on the Attack server.

In Firefox, go to

Log in as root with a password of toor as shown below.

On the next page, click the "Erase Comments" button.

Then inject a simple cookie-stealing XSS payload, as shown below.

The cookie appears in an Alert box, as shown below.

Task 2: Using a Data Viewer

You need some server that allows you to collect data from an HTTP request. We'll use one I put on the Attack32 server.

In a Web browser, go to

You see the Data Viewer, as shown below, with the message "No data received!" Click the link on that page.

Now you see "Results", as shown below.

Click the "View captured data" link.

At the bottom of the page, find the data you injected, as shown below.

Task 3: Putting it All Together

Create a payload that steals the cookie from the message board and sends it to the Data Viewer. Include your name in the data, as shown below.

You see your name and the stolen cookie, as shown below.


In Firefox, click the three-bar icon at the upper right, and click "Web Developer", "Web Console".

Then inject the script. The console will show you helpful error messages.

Saving the Screen Image

Make sure your name and a MD5 Cookie Value are visible, as shown above.

Capture a whole-desktop image and save it as "Proj 11x from YOUR NAME".

Turning in Your Project

Email the image to with a subject of "Proj 11x from YOUR NAME".

Posted 4-23-18
Troubleshooting tip added 4-23-19

Sam Bowne